Update dependency autoprefixer to v10.3.4

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
autoprefixer	10.3.3 -> 10.3.4

---

Release Notes

postcss/autoprefixer

### [`v10.3.4`](https://togithub.com/postcss/autoprefixer/blob/master/CHANGELOG.md#​1034) [Compare Source](https://togithub.com/postcss/autoprefixer/compare/10.3.3...10.3.4) - Fixed `stretch` value in latest Firefox.

---

Configuration

📅 Schedule: At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box.

---

This PR has been generated by WhiteSource Renovate. View repository job log here.